At present, with the developments of display technologies, transparent display technology as an emerging display technology has got more and more attention. When a transparent display substrate displays an image, the user can, through the transparent display substrate, see an object placed therebehind. The better the transparency effect is, the clearer the object behind the transparent display substrate is seen by the user through the transparent display substrate. Therefore, the test on the transparency effect of the transparent display substrate has become especially important.
In prior art, the following two methods are generally employed to test a transparent display substrate with a transparency effect measurement apparatus (see FIG. 1). In the first method, a test plate including black and white patterns is placed behind a transparent display substrate. Brightness LB of the black regions and brightness LW of the white regions in the test plate is detected through the transparent display substrate respectively by using a display color analyzer CA210. A brightness contrast parameter T between the black regions and white regions in the test plate is acquired based on the brightness LB of the black regions and the brightness LW of the white regions as well as the equation
  T  =                    L        W                    L        B              ×    100    ⁢          %      .      The transparency effect of the transparent display substrate is determined according to the brightness contrast parameter T, wherein the greater the brightness contrast parameter T is, the better the transparency effect of the transparent display substrate is. In the second method, firstly, brightness of the black regions and brightness of the white regions in the test plate are directly detected to acquire an initial contrast parameter T0. Then, a contrast parameter T between brightness of the black regions and brightness of the white regions is acquired through the transparent display substrate. A transparency effect parameter CR of the transparent display substrate is acquired based on the contrast parameter T and the initial contrast parameter T0 as well as the equation
  CR  =                    T        1                    T        0              ×    100    ⁢          %      .      The transparency effect of the transparent display substrate is determined according to the transparency effect parameter CR, wherein the greater the transparency effect parameter CR is, the better the transparency effect of the transparent display substrate is.
However, no matter which one of the above methods is employed to test the transparent display substrate, the test has to be performed under a certain illumination condition. Therefore, the test will be inevitably disturbed by ambient light, and the test accuracy of the transparent display substrate is thereby influenced.